The problem with that has to be something very basic - it isn't rocket
science after all.

File permissions, syntax errors, assumptions that hold true in a shell
session but not in a startup script (e.g. PATH and other environment
variables), any of those basic things could be hindering you.

If you could share the output of the startup script someone here could
likely spot the issue right away. Hopefully you've redirected the output
of your commands to a logfile to capture that output.